It is known that traditional hearing aids of the behind the ear type (BTE's), wherein the audio signal from a microphone is processed into a hearing impairment compensated signal and converted into a sound signal by a receiver that is placed in a behind the ear housing and then communicated to an earpiece via a sound tube, offer higher maximum sound pressure levels (SPL) than known hearing aids of the In the ear (ITE), completely in the ear canal (CIC), or receiver in the ear (RIE) types of hearing aids.
This generates a problem for people with moderate to severe hearing loss. ITE, CIC and RIE hearing aids are less conspicuous than traditional BTE hearing aids. This is due to the fact that ITE and CIC hearing aids do not have a BTE unit, and that RIE's have a much smaller BTE unit than traditional BTE hearing aids, because in a RIE hearing aid the receiver, which is a large component, is placed in an earpiece that is adapted to be placed in the ear of a user during use. Thus CIC, ITE and RIE hearing aids are all more attractive to a user than the traditional BTE hearing aids due to the fact that they are less conspicuous. This poses a risk that persons who acquire these less conspicuous CIC, ITE or RIE hearing aids will turn out to be disappointed by the performance of these hearing aids as compared to the traditional BTE hearing aids.
It is thus an object to provide a hearing aid by which it is possible to give the hearing aid user the benefits of a less conspicuous hearing aid and high hearing loss compensatory performance simultaneously.
According to some embodiments, the above-mentioned and other objects are fulfilled by a first aspect that pertains to a hearing aid with a receiver placed in a receiver housing, wherein said receiver is being configured to be placed at least partly in the ear canal of a user, and wherein the hearing aid further comprises a sound tube that is acoustically connected to a sound port opening of the receiver or receiver housing, and wherein the sound tube has a longitudinal extension in at least two directions, ant wherein the sound tube furthermore has a total length of at least 16 mm.
Hereby is achieved a hearing aid that is less conspicuous than traditional BTE hearing aids, because the receiver, which is a relatively large hearing aid component, is configured to be placed at least partly within the ear canal of a user during use. Furthermore, by connecting a sound tube to the receiver output port in order to convey the generated sound into the ear canal of the user during use, the acoustic resonance effect generated by the sound tube will increase the maximum acoustical output of the hearing aid which has the consequence that a hearing aid according to some embodiments with a sound tube construction as described above will be able to generate a higher sound pressure level within the ear cannel of a user during use than is achievable by a hearing aid of conventional design. This increased acoustical output has also the additional benefit that a hearing aid according to some embodiments will have an increased dynamic range as compared with conventional hearing aids known in the art. However, in order to achieve a sufficient resonance effect a sound tube of a sufficient length is needed, and simulations as well as measurements have shown that a sound tube of at least 16 mm is needed. Since the sound tube is connected to a receiver that is to be placed at least partly in the ear canal of a user it is not possible to use a straight sound tube that has a sufficient length to generate the resonance effect that is needed, because the ear canal of an average human is too short. Thus, by having a sound tube that has a longitudinal extension in at least two different directions a longer sound tube can be used, while at the same time being applicable in the limited space available in the ear or ear canal of a user, and at the same time generating a sufficiently high resonance effect that makes a higher amplification possible or enables the hearing aid according to provide a higher output sound pressure level.
According to some embodiments, the sound tube may at least in part abut to the receiver housing (i.e. the surface of the housing) along at least one of the two directions of the sound tube. Hereby is achieved a more compact and thereby smaller earpiece, which also makes it possible to account for a tradeoff between required length of the sound tube and available space in order to achieve the amplification that is needed in order to account for a hearing loss of a user.
Computer simulations have shown that sound tubes having a longitudinal extension that is shorter than the longitudinal extension of present day hearing aid receivers are not effective enough, i.e. the resonance effect is not large enough to provide adequate amplification. Thus, the longitudinal length of the sound tube is preferably larger than the longitudinal extension of the receiver.
According to some embodiments, the receiver housing is configured to be placed completely in the ear canal of a user during use. Hereby is achieved a less conspicuous hearing aid, because the relatively large receiver component is placed completely in the ear canal during use.
However, in an alternative embodiment the receiver housing may be configured to be placed at least in part in the concha or cimba concha, just below the triangular fossa of an ear of a user.
According to another embodiment the longitudinal length of the sound tube along one of the at least two directions may be larger than the longitudinal length of the receiver.
Normally a hearing aid receiver will generate a resonance around 3 kHz that is determined by the mechanical properties of the receiver. These are the stiffness of the receiver suspension system and the air volume behind the membrane, together with the mass of the moving system of the receiver and air in front of it. By connecting a sound tube to the receiver port opening the waveguide effect of the sound tube will create an additional resonance. For the tube length range of 20 mm to 24 mm the resonance will occur between around 3.5 kHz and 4.4 kHz.
It may be shown that in the simplest possible system, i.e. a system wherein a straight sound tube is connected to hard piston in one end and the other end being open will exhibit a resonance exactly at
            F      res        =          c              4        -        L              ,where c is the speed of sound that normally can be set to be 343 m/s (for dry air at 20 degrees Celsius), and L is the length of the sound tube.
Now in a real hearing aid, the system is much more complicated than the one described above. For example the piston is the membrane inside a receiver and it drives the front volume of air inside the receiver housing, the sound port and the sound tube. Finally, the end is defined by the ear canal and tympanic membrane and not merely by the open end of the sound tube. However, computer simulations and measurements (see for example FIG. 9, FIG. 10 and the associated description) have shown that the above formula for calculating the resonance frequency is a good approximation for a real system. Thus, for the real system it can be expected that the resonance frequency will be in the neighborhood of the one calculated according to the above formula. Hence, it may be deduced from the above mentioned formula that if the hearing aid according to some embodiments comprises a sound tube that has a length between 18 mm. and 26 mm. optimal resonance properties is achieved both regarding placement and size of the second resonance peak. In further preferred embodiments, the sound tube has a length between 20 mm. and 24 mm, and in a yet more preferable embodiment the sound tube has a length between 18 mm. and 24 mm.
According to some embodiments, the sound tube may have at least two different cross sectional areas. Hereby is achieved a way in which in which the resonance properties of the sound tube may be influenced. For example a resonance chamber may be formed by having an area of increased cross section along the length of the sound tube, preceded and followed by an area of lower cross section.
It has been found practical if according to some embodiments, the two different cross sectional areas both are larger than the area of the receiver port opening.
According to preferred embodiments, the hearing aid may comprise a sound tube with a substantially rectangular cross section. Hereby is achieved that a more compact earpiece may be produced.
In a particularly advantageous embodiment of a hearing aid, the sound tube may be formed as an integral part of an earpiece having a detachable electrical socket system. Hereby is achieved a self-contained unit wherein a receiver may be placed. This self-contained unit may be placed formed in a way so as to fit to a particular standard receiver that is used in RIE hearing aids today.
In some embodiments, the sound tube may be formed as a predefined part to be mounted on or at a receiver. Hereby is obtained a sound tube that is easy to use in conjunction with a receiver. Preferably, the sound tube is formed as an integral part of the earpiece, which thereby can provide mechanical support for the sound tube.
Alternatively, the sound tube may at least in part be formed as an integral part of the receiver housing. Hereby is achieved that a more compact and space saving unit.
According to preferred embodiments, the sound tube is manufactured by a Rapid Prototyping Technology, such as selective laser sintering (SLS) or stereolithography (SLA). Preferably the sound tube is formed as an integral part of an earpiece for a RIE hearing aid using SLA or SLS technology. Alternatively, the sound tube may be formed as an integral part of (for example a tip portion) a ITE or CIC hearing aid shell structure.
According to preferred embodiments, the hearing aid may comprise a sound tube that may be individually formed to have an end user related shape, cross section(s) and length in dependence of the acoustical performance required. This required acoustical performance may in an embodiment for example be a specific desired frequency specific amplification, and/or damping characteristic for feedback suppression. Thus, making it possible to design a sound tube that in conjunction with a specific receiver or receiver type, makes it possible to account for user specific needs, such as audiometric hearing loss. This could for example be done with the help of a dedicated software program that may run on a computer, for example a standard personal computer. The software program could be an extension of the regular software programs provided to hearing aid dispensers. When operating the software program, the dispenser can provide the audiogram and a 3 dimensional scan of the ear and/or ear canal of a potential hearing aid user as inputs to the program. Based on this input the software program then suggests which receiver should be used. This suggestion could be based on the available space estimated from the 3 dimensional scan and/or merely on the basis of the obtained or measured audiogram. The program then calculates the length, shape and form of the sound tube. In addition to this the effects of a possible vent in the earpiece can be accounted for. Finally, the earpiece with sound tube (and possible a vent), and room for the suggested receiver is designed as a 3 dimensional model by the software program and may then be printed by a rapid prototyping technology such as SLS (selective laser sintering) or SLA (stereolithography). Instead of letting the software program suggest a receiver, the receiver type available could be provided as input to the software program.
In other embodiments, the hearing aid may comprise a microphone that, during use, is configured to pick up sound from within the ear canal of a user. Preferably, the microphone is placed in an earpiece that is adapted to be placed in the ear of a user during use, for example it may be placed adjacent to the receiver or be built into the same housing structure as the receiver. In one embodiment sound is transmitted from within the ear canal to the microphone via a second sound tube that during use has an open end that substantially faces the tympanic membrane of a user, and another end that is connected to the microphone. Hereby is achieved a hearing aid wherein the so called occlusion effect may be measured and, hence accounted for.
The microphone may also be configured to pick up sound from outside the ear canal, or alternatively, the earpiece may comprise a further second microphone that is configured to pick up the ambient sound surrounding a user. Hereby is achieved that the natural frequency shaping of the ambient sound field that is done by the outer ear or pinna may be utilized directly. Furthermore, for those embodiments that also comprise a BTE unit, this makes it possible to manufacture an even smaller BTE unit because two relatively large components, the receiver and the microphone(s) are all placed in the earpiece.
In order to preclude clogging of the sound tube by cerumen, the sound tube or earpiece may be equipped with a cerumen filter.
According to an alternative embodiment the hearing aid may comprise a sound tube with a cross sectional area that increases gradually or stepwise or partly gradually and partially stepwise along at least a part of the longitudinal extension of the sound tube from the receiver port opening.
A second aspect pertains to a hearing aid with a receiver that is adapted to be placed at least partly in the ear canal of a user, the receiver comprising a motor and a receiver housing, characterized in that the receiver housing has a integrally formed sound tube which has a longitudinal extension in at least two directions and wherein the sound tube has a total length of at least 16 mm.
A third aspect pertains to a hearing aid which comprises a behind the ear (BTE) unit configured to convert and process sound into an electrical signal and a signal conductor configured to communicate said electrical signal to an earpiece, wherein said earpiece comprises a receiver that is configured to convert said electrical signal into a sound signal, characterized in that the earpiece comprises a sound tube that is connected to the sound port opening of the receiver and having a longitudinal extension in at least two directions.
In accordance with some embodiments, a hearing aid includes a receiver with a receiver housing, the receiver having a sound port opening, and being configured to be placed at least partly in an ear canal of a user, and a sound tube acoustically connected to the sound port opening of the receiver, the sound tube having a longitudinal extension in at least two directions, wherein the sound tube has a total length of at least 16 mm.
In accordance with other embodiments, a hearing aid includes a receiver that is configured to be placed at least partly in an ear canal of a user, the receiver comprising a motor and a receiver housing, and a sound tube having a longitudinal extension in at least two directions, wherein the sound tube has a total length of at least 16 mm, wherein the receiver housing is integrally formed with the sound tube.
In accordance with other embodiments, a hearing aid includes a behind the ear (BTE) unit configured to process sound and generate an electrical signal, an earpiece, and a signal conductor configured to communicate the electrical signal to the earpiece, wherein the earpiece comprises a receiver that is configured to convert the electrical signal into a sound signal, and wherein the earpiece further comprises a sound tube that is coupled to a sound port opening at the receiver, the sound tube having a longitudinal extension in at least two directions.
While several embodiments of three aspects have been described above, it is to be understood that any feature from an embodiment of one of the aspects may be combined with any feature(s) from embodiment(s) of any other aspect(s). Thus, when the term “embodiment” or “embodiments” is used in the specification, it is understood that it can be an embodiment or embodiments according to any one or combination of the three aspects, or any one or combination of any of the features associated with the three aspects.